The Lexington Tree Bylaw, Explained: Permits, $200/Inch & Real Costs

Most Lexington homeowners meet the Tree Bylaw the same way: a bulldozer is idling in the driveway, the foundation guy is pointing at the oak in the side yard, and someone is googling "lexington tree bylaw" with mild panic. That is the right time to learn that a protected tree can cost $200 per inch to remove during construction — but it is about six months later than ideal. I'm Keith McDonald. McDonald Tree Service has been filing Lexington tree permits since the bylaw existed in its earlier, cheaper form. What follows is the working version we walk homeowners through on every estimate, written like a guy leaning on a chip truck and not like a paragraph of town code.

Plain-English Summary

The Lexington Tree Bylaw is Chapter 120 of the Town of Lexington Code. It exists to protect mature trees on private property — primarily during teardowns, additions, and major construction. The town adopted the original bylaw to slow the canopy loss that comes with constant residential redevelopment, and amended it in 2024 with the 4x multiplier to put real cost on removing the biggest trees. (Translation: the town watched developers level oaks for fifteen years and decided enough was enough.)

Here is the entire bylaw in one paragraph for the homeowner who just wants to know:

If you are doing major construction or demolition on your Lexington property, every tree 8 inches in diameter or larger inside your setback zones is protected. Removing one requires a Tree Warden permit and mitigation — replanting equivalent caliper or paying $200 per inch into the town tree fund, plus a $20-per-inch permit fee. Trees 24 inches and larger trigger 4x mitigation. Hazardous trees are exempt from mitigation but still need the permit. Routine maintenance removal with no construction in progress is not regulated by the bylaw.

That is it. The full text is six pages of legal definitions and procedural details; the practical effect for almost every homeowner is in that paragraph. The other five and a half pages are for the lawyers.

When the Bylaw Applies to You

Situation	Bylaw Triggered?	What You Need
Routine removal, private property, no construction	No	Just hire a tree service
Pruning, no construction	No	Just hire a tree service
Major construction or demolition + tree 8"+ DBH in setback	Yes	Tree Warden permit + $200/inch mitigation or replanting + $20/inch fee
Construction + tree 24"+ DBH in setback	Yes — 4x	Tree Warden permit + $800/inch mitigation or 4x caliper replanting + $20/inch fee
Hazardous tree, any size, anywhere	Permit yes, mitigation no	Tree Warden permit only ($20/inch fee)
Public shade tree (right-of-way)	Always — MGL Ch. 87	Tree Warden hearing + public notice
Tree within 100 ft of wetland	Conservation Commission	Notice of Intent under MGL Ch. 131 §40
Tree in a designated historic district	Yes + Historical Commission	Standard bylaw + Historical review

The single most important word above is construction. The bylaw is built around the construction trigger. If you are not building, demolishing, or adding to your house, the bylaw is almost certainly not going to apply to your removal. The dead maple in your backyard that has been on death row for three winters can come down without anyone at town hall caring.

What "Setback" Actually Means

The setback zones are the bands around the perimeter of your lot where the bylaw protections apply:

• 30 feet from the front property line
• 15 feet from each side property line
• 15 feet from the rear property line

Trees in the middle of the lot — outside those bands — are not protected by the Tree Bylaw even during construction. That is the loophole, and developers used to lean on it hard. The 2024 amendments tightened the front-yard replanting requirement in response, but interior-of-lot mature trees are still unprotected by the bylaw if they are outside the setback. (I have been climbing trees for thirty years and I still ask the homeowner where the property line is before I start measuring, because the wrong answer to that question costs everyone an extra trip to the assessor's office.)

DBH is "diameter at breast height" — the trunk diameter measured 4.5 feet above the ground, which is roughly chest height on me and shoulder height on shorter homeowners trying to picture it. Most healthy backyard oaks and maples on Lexington lots blow past 8 inches by their twentieth birthday. The 24-inch threshold for the 4x multiplier is roughly a tree that has been there for 60 to 100 years — old enough that it was probably here when the colonial out front was being built.

The Mitigation Math, With Real Examples

This is where the bylaw gets real. The mitigation requirement during construction can be paid in two ways: replant equivalent caliper trees, or pay $200 per inch into the town tree fund. Most homeowners and developers end up paying, because finding planting space for 30 inches of caliper on a 0.4-acre teardown lot is rarely practical. There is a kind of Sopranos pricing energy to "$200 per inch" — Lexington isn't asking, it's quoting, and the discount for not paying is "leave the trees standing."

Tree DBH	Standard Mitigation	4x Mitigation (24"+)	Permit Fee	Total (Pay)
8 inches	$1,600	—	$160	$1,760
12 inches	$2,400	—	$240	$2,640
18 inches	$3,600	—	$360	$3,960
24 inches	—	$19,200	$480	$19,680
30 inches	—	$24,000	$600	$24,600
36 inches	—	$28,800	$720	$29,520

For a teardown with three large protected trees in the setback, you are looking at potential mitigation in the $50,000 to $100,000 range — separate from the actual tree removal cost. That is the part that surprises developers who priced their build assuming Lexington was just another suburb. It isn't. The bylaw is the receipt on that.

For an existing homeowner adding a garage or finishing a foundation, the math is usually much smaller. A 14-inch protected ash in the side setback that has to come down for the foundation pour: $2,800 mitigation + $280 permit + $700 removal = roughly $3,800 all in. Build it into the project budget the way you would the dumpster and the dump fees; it should not blow up the job.

The Hazardous-Tree Exemption

This is the carve-out that protects most homeowners from the bylaw's teeth. A tree that is genuinely hazardous — dead, structurally compromised, leaning after a storm — can be removed under a permit that is exempt from the $200-per-inch mitigation fee. You still file the paperwork, but you do not owe the mitigation.

Documentation matters. What the Tree Warden wants to see:

• Photographs showing the hazard (lean, crack, dead canopy, exposed roots, fungal conks)
• A written assessment from a qualified arborist (we provide these on every Lexington estimate)
• Identification of the target — what would the tree hit if it fell?
• Estimated probability and consequence of failure

Dead trees almost always qualify. Trees with mushroom growth at the base usually qualify (fungal root rot; mushrooms on a tree are roughly what a check-engine light is on a car — not great news). Trees with a recent lean from a windstorm qualify. Healthy trees with deadwood in the canopy generally do not — those need pruning, not removal. We give them a haircut. They look better. They do not tip.

A note from the field: I have had homeowners call sure their tree was on death row, and after a walk around the trunk and a look at the canopy I have told them to keep it. A $400 prune and a few deadwood cuts is not a $4,000 mitigation event. We will happily talk you out of a removal you do not need. The opposite call happens too — a tree that looked fine from the kitchen window but had bark sloughing off a leader and a fungal conk at the base. Same job, opposite recommendation. Either way, the conversation starts with what the tree actually needs, not what is easiest to bill.

Process & Timeline

1. Site visit and assessment. We walk the property, measure DBH on every tree that might be in play, identify which are in setback zones, and tell you which the bylaw will affect. This is part of every Lexington estimate.
2. Permit application. We complete the Tree Warden application — tree species, DBH, location, reason for removal, mitigation proposal (replanting plan or payment). For hazardous trees we attach the arborist letter and hazard photos.
3. Tree Warden review. 2 to 4 weeks for a straightforward application. The Tree Warden can request a site visit or additional documentation. We respond to those requests within 48 hours.
4. Approval and posting. Approved permits are posted on the property for 7 days before removal. Hazardous trees can be removed immediately under the hazardous-tree provision.
5. Removal and replanting. We do the work. If you chose replanting, we plan the new tree locations with the Tree Warden's approval before the original removal.
6. Sign-off. Tree Warden inspects the work or the replanting and closes out the permit.

For wetland-buffer trees, add 4 to 8 weeks for Conservation Commission review under MGL Chapter 131, Section 40. For public-shade trees, add 4 to 6 weeks for the public hearing.

Historic District Overlay

About 2,000 Lexington properties sit within local historic districts — Battle Green, Munroe Tavern corridor, parts of Massachusetts Avenue, sections of the streets near the Minuteman National Historical Park. Tree work on these properties gets reviewed by the Historical Commission in addition to the Tree Warden when the removal would change the visible streetscape character.

This rarely blocks a removal outright, but it adds a review step and 2 to 4 weeks of timeline. Heritage trees — the ones standing when the Revolution was being fought — get the highest scrutiny, which is fair. If the tree predates the country, we can wait three more weeks for paperwork.

Replanting vs. Paying — How to Decide

The bylaw lets you mitigate by replanting equivalent caliper. The math:

• A 2-inch caliper nursery tree (typical replanting size) costs $400 to $700 installed
• To mitigate a 20-inch removed tree, you need 20 inches of caliper — so 10 of those 2-inch trees
• Total replanting cost: $4,000 to $7,000
• Cash mitigation alternative: $4,000 (20 inches × $200)

For small protected trees (8 to 16 inches DBH), paying is often slightly cheaper than replanting. For 4x trees (24"+), replanting is usually significantly cheaper because you are working against an $800-per-inch number. A 30-inch oak: $24,000 cash, or roughly $12,000 in replanting if you can fit the trees. The math tilts hard toward planting once you cross the 4x line.

There is also the question of where to plant. If your lot is small or already heavily treed, you may not have space for the replanting. In that case the cash option becomes the only real choice. The Tree Warden's office can advise on suitable planting locations.

What Counts as "Major Construction"

This is the trigger and it is worth being precise:

• Triggers the bylaw: teardown and rebuild, foundation pour for an addition, new garage construction, septic system installation requiring excavation, swimming pool installation, driveway expansion involving grading
• Does not trigger: roof replacement, siding work, interior renovation, deck rebuild on existing footprint, fence replacement, landscaping that does not require regrading

The grey area is partial demolition. If you are taking down a chimney or a wall but not foundation-touching, the trigger is judgment-call territory. Talk to the Building Inspector and Tree Warden before you assume.

What This Means for Buying a Teardown Property

If you are buying a Lexington property to demolish and rebuild, the tree obligations are part of your project cost. Before you close, walk the lot and identify every protected tree:

• Map the setback zones (30/15/15 ft)
• DBH every tree inside the setbacks
• Categorise by size: under 8" (no obligation), 8 to 23" ($200/inch), 24"+ ($800/inch)
• Calculate your worst-case mitigation
• Decide which trees can stay in your construction plan

We do these pre-closing assessments for buyers regularly. A walkthrough costs nothing and can save you from a $40,000 surprise three months into the project. Lexington loses 75 to 80 homes a year to teardowns; the bylaw is what keeps the tree canopy from going with them. (Yes, I have walked teardown lots in February in a coat I should have replaced two winters ago. The job does not care.)

Don't Try to Work Around It

I will say this once because it matters. The bylaw has real teeth. Removing a protected tree without a permit during construction can stop your project, trigger restoration requirements at the developer's cost, and lead to fines significantly larger than the mitigation would have been. The Tree Warden notices missing trees on a construction site the way a parent notices a missing cookie — fast, and with a follow-up question.

The straight path is to plan for the bylaw, file the permit, pay the mitigation, and move on. The shortcut path is a much bigger problem than the cost it tries to avoid.

How We Help

For every Lexington homeowner we work with, we handle the bylaw in-house: pre-removal assessment, DBH measurement, hazard documentation, permit application, mitigation proposal, replanting coordination if you choose that route, and Tree Warden sign-off. You do not chase the town. That is on us.

For Lexington-related tree work, see the tree removal in Lexington cost guide, the general Lexington tree service overview, or the 24/7 emergency response page. For the town's own resources, visit the official Tree Bylaw page or the Lexington Tree Committee.

Get a Bylaw-Aware Estimate

Call (978) 375-2272. I will walk your property, identify which trees the bylaw affects, calculate the mitigation, and give you a flat quote with the permit fees broken out separately. No surprises. Worst case you spend a phone call and learn the bylaw does not apply to you at all — which is the answer for most routine residential removals in Lexington. The bylaw is not going anywhere. The trees, eventually, are. Better to call before the bulldozer does.